1. Field of the Invention
The present invention relates to a graphitization furnace for graphitization of carbon bodies, a system that includes a plurality of such graphitization furnaces, and a graphitization method.
2. Description of the Related Art
Furnaces conventionally used for graphitization of carbon bodies include an LWG (Length-Wise Graphitization) furnace or the like. The LWG furnace may be used to produce graphitized electrode bodies that are typically cylindrical in shape.
The LWG furnace is provided with a hood that covers a furnace chamber. The hood is opened when loading the carbon bodies inside the furnace chamber and supplying a pack material such as coke into the furnace chamber prior to heating to a graphitization temperature, and is closed during a graphitization process. The carbon bodies are buried in the pack material for heat insulation and anti-oxidation. The hood is also opened when collecting the pack material and unloading the graphitized electrode bodies from the furnace chamber after the graphitization process and a lapse of a sufficient cooling time. The loading of the carbon bodies and the unloading of the graphitized electrode bodies into and from the furnace chamber, respectively, are performed by a loading and unloading mechanism. Further, the supplying and collecting of the pack material into and from the furnace chamber, respectively, are performed by a supplying and collecting mechanism. After the pack material is collected and the graphitized electrode bodies are unloaded from the furnace chamber, the LWG furnace is reused for a next graphitization process.
Accordingly, the unloading of the graphitized electrode bodies from the furnace chamber depends on the cooling time, an efficiency of the supplying and collecting mechanism that collects and removes the pack material from the furnace chamber after the graphitization process in order to enable unloading of the graphitized electrode bodies, and an efficiency of the loading and unloading mechanism that unloads the graphitized electrode bodies from the furnace chamber. Because it is difficult to reduce the cooling time in the case of self-cooling, and a cycle with which the LWG furnace is reused depends on the cooling time and an operation time of the supplying and collecting mechanism particularly during collection of the pack material, a high-productivity system is difficult to design.
On the other hand, an apparatus for the production of graphite from carbon bodies, having a refractory lined open-topped metal and generally U-shaped shell furnace, is proposed in U.S. Pat. No. 4,394,766, for example. The proposed apparatus is provided with a means to remove a thermal insulation medium by gravity dumping through a bottom of the furnace. However, electrodes are removed from the furnace by a stock extractor after a predetermined cooling period, and the thermal insulation medium is thereafter dumped into hoppers.
For this reason, according to this proposed apparatus, a considerably long cooling time would be required if the electrodes were to be removed from the furnace after the electrodes have cooled down to a low temperature. Otherwise, the electrodes would have to be removed from the furnace when the electrodes are still at a high temperature. On the other hand, if the thermal insulation medium were dumped from the furnace before removing the electrodes, the electrodes would fall to the bottom of the furnace. In this case, the electrodes at the bottom of the furnace may interfere with the dumping of the thermal insulation medium from the furnace. In addition, it may become difficult for the stock extractor to remove the electrodes at the bottom of the furnace.
Consequently, it is conventionally difficult to design a high-productivity system for the graphitization of the carbon bodies.